[PATCH] Input: elan_i2c - check if device is there before really probing

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Before trying to properly initialize the touchpad and generate bunch of
errors, let's first see it there is anything at the given address. If we
get error, fail silently with -ENXIO.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/input/mouse/elan_i2c_core.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/input/mouse/elan_i2c_core.c b/drivers/input/mouse/elan_i2c_core.c
index 5d3b53dd2fa2..0479730e7c5c 100644
--- a/drivers/input/mouse/elan_i2c_core.c
+++ b/drivers/input/mouse/elan_i2c_core.c
@@ -1040,6 +1040,7 @@ static int elan_probe(struct i2c_client *client,
 	const struct elan_transport_ops *transport_ops;
 	struct device *dev = &client->dev;
 	struct elan_tp_data *data;
+	union i2c_smbus_data dummy;
 	unsigned long irqflags;
 	int error;
 
@@ -1091,6 +1092,14 @@ static int elan_probe(struct i2c_client *client,
 		return error;
 	}
 
+	/* Make sure there is something at this address */
+	error = i2c_smbus_xfer(client->adapter, client->addr, 0,
+			       I2C_SMBUS_READ, 0, I2C_SMBUS_BYTE, &dummy);
+	if (error) {
+		dev_dbg(&client->dev, "nothing at this address: %d\n", error);
+		return -ENXIO;
+	}
+
 	/* Initialize the touchpad. */
 	error = elan_initialize(data);
 	if (error)
-- 
2.13.0.rc1.294.g07d810a77f-goog


-- 
Dmitry